ML20209J411
| ML20209J411 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/06/1985 |
| From: | Thompson H Office of Nuclear Reactor Regulation |
| To: | NORTHEAST NUCLEAR ENERGY CO. |
| Shared Package | |
| ML20209J395 | List: |
| References | |
| NUDOCS 8511110473 | |
| Download: ML20209J411 (13) | |
Text
7590-01 ENCLOSURE 1 UNITED STATES OF AMERICA f.'l! CLEAR REGULATORY COMMISSION In the Matter c#
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NORTliEAST NUCLEAR ENERGY COMPANY
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Docket No. 50-245
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EXEMPTION I.
The Northeast Nuclear Energy Company (the licensee), et al., is the holder r f Provisinnel Operating License No. DPR-21 which authorizes operation of the Millstond Nuclear Power Station, Unit No.1.
The license provides, among other things, that it is sub.iect to all rules, regulations and Orders of the Commis-sion now or hereafter in effect.
The Millstone Unit No. 1 plant power source is a boiling water reactor located at the licensee's site in the town of Waterford, Connecticut.
II.
On November 19, 1980, the Commission published a revised Section 10 CFR 50.48 and a new Appendix R to 10 CFR Part 50 regarding fire protection features of nuclear power plants (45 FR 76602). The revised Section 50.48 and Appendix R
.. became effective on February 17, 1991.Section III of Appendix R contains fifteen subsections, lettered A through 0, each of which specifies requirements for a particular aspect of the fire protection features et e nuclear power plant.
One of these fifteen subsections, III.G., is the subject of this exemption request. Specifically, Subsection III.G.? requires that one train of cables and equipnent necessary~te achieve snd raintain safe shutdown be maintained free of fire damage by one of the following means:
8511110473 851106 PDR ADOCK 05000245 F
7590-01
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Separation of cables and equipment and associated non-safety circuits of redundant trains by a fire barrier having a 3-hcur rating. Structural steel forming a part of or supporting such fire barriers shall be protected to providt fire resistance equivalent to that required of the barrier; b.
Separation of cables and equipment and associated rfo'n-safety circuits or redundant trains by a horizontal distance of more than 20 feet with no intervening combustibles or fire hazards.
In additior., fire detecters and an autorratic fire suppression system shall be installed in the fire area; cr c.
Enclosure of cables and equipment and associated non-safety circuits cf one rederdant train in a fire barrier having a 1-hour rating. 'In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
III.
Sy letters dated March 1, and July 16, 1982 as supplemented by letters dated April 15, 1983, December 4,1984, August 7 and 23,1985, the licensee requested exemptions from the reovirements of Section III.G of Appendix R, to the extent that it requires physical separation and/or fire protection systems to protect redundant trains of safe shutdnwn related cable and equipment. The acceptability of the exemption requests for each of the five fire areas !s addressed below. Details are contained in the NRC staff's related Safety Evaluation.
The fire areas related to tha five exemptions are:
(1) Main Control' peer (Fire Area T-21)
(2) Turbine Building Reactor Feed Pump Area, Elevetion 14'-6" (Fire Area T-5 BandC)
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i b (3) Turbine Building Switchgear Area (T-19A), Elevation 34'-6" (4) Turbine Building Switchgear Area (T-19 CD and E), Elevation 34'-6" (5) Reactor Building - Northeast, Elevation 42'-6" (Area R-19)
Exemption 1 Main Control Room (Fire Aree T-?!)
The control room is not in compliance with Section III.G because of the lack of adequate physical separation between redundant shutdown divisions e.nd the lack of an alternate shutdown capability independent of the control recr.
The Unit I control room is enclosed by complete reinforced concrete con-struction except at the common boundary with the Unit 2 Control Room, where a smoke barrier (metal panel and glass) is installed. All cpenings are protected by deors, dampers or fire reted penetration seals. Also, in all other plant locations, redundant safe shutdown divisions ere separated and protected so that one division will remain free of fire damage. There is, therefore, reasonable assurance that a fire that occurs outside of the control room will affect only one shutdown division within the control room and because the control room is a separate fire area from the rest of the plant, a fire that occurs anywhere else in the plant will not endanger control room operators.
The fire hazard within the centrol room is low.
In-situ ccabustible mate-rials consist mainly of paper, cable insulation within the control panels, and small quantities of transient combustibles. The quantity, nature, and distri-bution of the in-situ combustibles is such that if a fire were to cecer, it wneld rot propagate quickly or extend over a large area of the control room.
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a t) The hazards associated with transient combustible materials will be further mitigated to a limited extent by the shift inspecticrs end the licensee's admin-istrative controls. While these measures by themselves are not enough to ensure that additional accumulatiers of combustible materials will not occur, they will reduce the probability of having them.
Because the ' control room is con-tinuously manned and because a fire detection system is present in all areas outside of the normal line of sight of the operators, any potential fire will be detected in its incipient stages. This early fire warning capability, coupled with the portable fire fighting equipment in the room, provides reasonable assurance that a fire will be discovered and suppressed before reaching a sig-nificant magnitec'e. The staff, therefore, concluded that a fire located away from the control panels will not pose a direct threat to safe shutdown systems in the panels.
Because of the limited spatial separation between redundant shutdcwn divi-sions in either the auxiliary panels or the main control console, a fire at or within the panels has the potential for damaging both divisions. Protection against this hazard will be achieved by the installation of seals at the floor around the panels and console which will prevent a spilled flammable liquid fron f1 cuing into the cabinets. Additional protection against this hazard will be the automatic Halon 1301 fire suppression system that will be ir. stalled to protect the entire main control room. The customized administrative controls and the need to keep the space around the panels free of obstruction for operator access, will help preclude accumuletions of combustibles to a significant degree.
If a fire should occur at, necr, or within the panels, the fire or fire sup-pression activities, such as the discharge of a portable fire extinguisher, may cause a loss of function of a portion of the main control-board or auxiliary
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. control panels. Safe shutdown conditions could still be achieved and maintained via the alternate shutdown capability.
The licensee has committed to provide an automatic halon fire suppression system. The suppression system also has the capability for manual activation if the operators become aware of a fire before the fire detection sensors.
The staff concluded that any potential fire that occurs within the main control board will be rapidly detected and either automatically or manually suppressed before serious damage occurs.
Lecal fire damage to the panels is also possible. Staff opinion is that, because of the limited nature of the fire hazards and the level of fire protec-tion in the control room, the worst damage is the complete loss of two ad,iecent panels in the main control console or one enclosed auxiliary control panel.
The licensee will have provisions for safe shutdown if fire causes a loss of function to the shutdown systens in any one of the four control room fire zones.
The staff found this acceptable.
The remaining concern involved control room habitability. Because the achievement of safe shutdown after a fire in the control room is dependent on some undemaped safe shutdown systems in the room, fire effects have to be limited so that safe shutdown can be achieved and maintained if control room evacuation becomes necessary for a period of time.
Because of the limited fire hazards in the control room, the continucus presence of control room operators and the added fire protection proposed by the licensee, including an automatic Halon fire suppression system, the effects of a fire in the control room would not be serious enough to cause long term
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. evacuation. The staff judged that control room habitability could be reestab-lished within or.e heur if evacuation became necessary, with reliance upon the merual smoke removal system, portable exhaust fans, and self-contained breathing apparatus.
The licensee will have provisions for safe shutdown if the centrol room remains habitable during a fire or if evacuation is necessary for up to one hour. The staff therefore concluded that there is reasonable assurance that under all credible fire scenarios for the control room, a capability to achieve and maintain safe shutdown conditions will remain free of fire damage.
Based on the above evaluation, the staff concluded that the existing fire protection with the proposed modifications will provide a level of fire protec-tion equivalent to that provided by Item III.G.P. Additional modifications needed to meet the requireirents of Section III.G of Appendix R would not signifi-cantly increase fire safety of the plant. Therefore, the staff finds the licensee's request for exemptfor, from Section III.G.2 of Appendix R to 10 CFR Part 50, for the control room acceptable.
Exemption 2 Turbine Building Reactor Feed Pump Area, Elevation 14'-6" (Fire Area T-5 B and C)
The recuirements of Section III.G.2 were not met because of the lack of an area-wide automatic fire suppression systm.
The Terbine Building is censidered a single fire area. Within it, the licensee has identified the Reactor Feed Pump Aree es a location where automatic sprinkler protection has not been provided per Section III.G.2.c.
Safe shutdown equipment present in this location consists of reactor feed pumps A and 0; supportira lube oil pumps A and B; and motor control centers (MCC) 2-4 and 2A-4.
Shutdown-related cables in this location are listed in the licen:ce's April 15, 1983 submittal.
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j A fire of significant magnitude could cause the loss of redundant shutdown systems. However, the feed pump area is protected by an automatic fire detec-tion system which alams in the Control Room.
If a fire should occur, it would be detected in its formative stages before significant temperature rise or flame propagation occurs. - The plant fire brigade would then be. dispatched to the area to extinguish the fire using the manual fire fighting equipment available in the area.
If rapid fire' spread occurred before the arrival of the brigade, the exist-ing and proposed sprinkler systems would actuate to limit fire spread, reduce room temperatures and protect the shutdown-related components. The cable fire-barrier will protect one division of redundant shutdown-related cables from dama ge.
All other shutdown systens have redundant counterparts in other fire areas or are required only for cold shutdown and can be repaired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
There is, therefore, reasonable assurance that if a fire occurred in the feed l
punp area, safe shutdown could be achieved and maintained.
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Existing fire protection includes: partial automatic sprinkler protection;
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a fire detection system; cable tray fire stops; manual hose stations and portable
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fire extinguishers.
In the April 15, 1983 letter, the licensee comitted to protect one train of the redundant energency diesel generator power and control i
cables in a 1-nour fire-rated barrier and to protect these cables by an automatic sprickler system.
Based on this infomation, the staff concluded that the licensee's alter-nate fire protection configuration will achieve an acceptable level of fire protection equivalent to that provided by Section III.G.2. Therefore,.the staff I
finds the licensee's reouest for exemption for the Reaccor Feed Pump Area acceptable,
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8 Exemption 3 Turbine Building Switchgear Area (T 19A) Flevation 34'-6" (Area 19-AJ The requirements of Section III.G.2 are not met because the redundant switchgear and associated cable are not completely separated by a 1-hour fire-rated barrier and are not completely protected by an automatic fire suppressier system.
The Turbire Building is a single fire area. Within it, the licensee has identified the Switchgcar Area T-19A as a location where automatic sprinkler protection has not been provided throughout.
Safe shutdown equipment in this location consists of redundant shutdcen-related switchgear. Shutdown cables in this location are listed in the licensee's April 15, 1983 submittal.
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Existing fire protection includas a complete fire detection system, manual hose stations, and portable fire extinguishers.
Ir, the April 15, 1983 letter, the licensee coteitted to install an automatic deluge-type water spray system actuated by heat detector and a concrete curb / dike to protect switchgear in this locetien from its redundant counterpart in Switchgear Area T-19CDE. The licensee also comitted to protect one division of shutdown-related cables from a fire in zone T-19B to a point 60 feet beyond its redundant switchgear located in area T-19A.
The NFC concern was that a fire of significant magnitude could cause the loss of these systems. However, the principal fire hazard to the switchgear and cables is combustible cable insulaticr. Eecause these cables are coated with a fire retardant, the staff concluded that a fire in them would not burn rapidly or with initially-high heat release. A fire wruld be detected early by the fire detectier system. The fire brigade wculd then be dispatched to extin-guish the fire using the manual fire fighting equipment that is eveiltble.
Pending errival of the brigade, the deluge system between the switchgear seculd
7590-01 m activate and discharge water automatically in a " curtain" pattern. This concept has been used successfully to protect openings in fire walls and floor / ceiling assemblies and, therefore, provide reescrable assurance that switchgear from one division will remain undamaged. Also, the cenbination of a 1-hour fire-rated barrier with the 60 feet of separation between shutdowr, cable and its redundant switchgear will provide sufficient passive protection until the fire is put out.
Pased on this understanding, the staff concluded that the licensee's elter-nate Vire protecticn configuration, will achieve an acceptable level of fire protection equivalent to that provided by Section III.G.P. Therefore, the staff finds the licensee's reovert for exemption for the Switchgear Area (T-19A) acceptable.
Exemption 4 Turbine Building Switchgear Area, Elevation 34'-6" (Area T-19C, D, E)
The reouirements of Section III.G.2 are not met because redundant switch-gear are not completely protected by a 1-hour fire barrier erd are not completely protected by an automatic fire suppression system.
The Turbine Building is a single fire area. Within it, the licensee hes identified Switchgear Area T-19C,D,E as a lccation where automatic sprinkler prr-tection has not been provided throughout.
Safe shutdown ecufprent in this location consists of redundant switchgear; 125-VDC motor control center DC 11-A-3; battery chargers 1, lA, erd 11.A; cr.d the 4V bus tie from bus #7 to bus #3. Shutdown tables in this location are listed in the licensee's April 15, 1983 submittal.
Existina fire protection includes a pre-action type sprinkler system for the seal oil unit and lift pumps; a fire detection system; renual hose stations and portable fire extinguishers.
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. In the April 15, 1983 submittal, the licensee comitted to install a 3-lour fire barrier to protect all the S-2 train shutdcwn related ca'ules, the service water pump cables and the S-P D.C. switchgear.
In addition, an automatic deluge system and curb / dike will be installed to protect the switchgear in this loca-tion from its redundant counterpart in Switchgear Area T-19B.
The switchgear area is protected by an early-warring fire detection system which alarms in the control room. There is reasonable assurance that if a fire shculd occur, it will be detected and suppressed early by the plant fire brigede.
Urtil the fire is suppressed, the proposed deluge system and 1-hour fire-rated barriers will provide protection to one division of shutdown systems so that a safe shutdown capability will be available during and after a fire.
Based on the ebeve, the staff concluded that the licensee's alternate fire protection configuration, will achieve an acceptable level of fire protection equivalent to that provided by Secticn III.G.2.
Therefore, the staff finds the I
licensee's request for exemption for the Switchgear Area (T-19C,D,E) acceptable.
Exemption 5 Reactor Building-flertheast, Ele"ation 42'-6" (Area R-19)
The technicel reovirements of Section III.G.E are not met because the redundant instrument racks and related pneumatic tubing are not completely separated by a 3-hour fire-rated barrier.
The Reactor Building is a single fire area.
k" thin it, the licensee has identified the northeast corner of eleveticn 42'-6" as a location where a com-plete-3-hour fire rated barrier does not exist between redundant instrument racks.
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7590-01 11 Safe shutdown systems in this location consist of the following equipment:
Reactor Building closed cooling water pumps Reactor Building closed cooling water heat exchangers Reactor and recirculation pump instrument racks Isolation condenser cendensate return valve Isolation condenser valve transfer switches Potor control center Existing fire protection consists of an autenatic deluce sprinkler system for the notor generator set arees; P wet pipe sprinkler system for cable tray protection; a fire detection systen; manual hose stations and portable fire extinguishers.
The licensee fustified the exemptinn on the basis of the existing fire protcction, the construction of the instrument racks and related pneumatic tubing, ar.d the 30-40 feet of soatial separation between redundant racks and tubir.g.
The staff was concerned that because a complete 3-hour wall did not exist between the redundant instrument racks, they could both be damaged if a fire occurred in this location. The areas where combustible materials are concen-trated are protected by Putomatic fire suppression systems.
In addition, this location is protected by a fire detection system which alarms in the control If a fire should occur, it vould be detected in its formative stages, room.
before significant flame propagation or temperature rise nccurred.
It would then be suppressed by the fire brigade using manual fire fighting equipment.
If a fire originated on either side of the existing wing wall A ich sepa-rates both instrunent racks, the wing wall would ect es a shield to protect the
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instrument rack from direct flame impingement and radiant energy.
If a fire were located at the leading edge of the wall, "1 automatic sprinkler system would actuate to suppress the fire, reduce reem temperatures and protect the racks. Until the fire is suppressed, the 40 feet of spatial separation between the racks and the 1/4-inch steel plate rack enclosures wo~uld provide a degree of passive fire protection to provide reasonable assurance that at least one rack would remain free of fire damage.
Based on the above, the staff concluded that the licensee's alternate fire protection configuration will achieve an acceptable level of fire protection equivalent to that provided by Section III.G.2. Therefore, the staff finds the licensee's request for exemption for the northeast corner of the Reactor Building on elevation 42'-6", area R-19 acceptable.
IV.
The Commission has determined that, pursuant to 10 CFR 50.12, these exemp-tions as described in Section III are authorized by law and will not endanger life or property or common defens and security and are otherwise in the public interest. Therefore, the Commisison hereby grants the exemption requests identified in Section III above.
Pursuant to 10 CFR 51.32 the Comission has determined that the granting of these Exemptions will not result in any significant environmental impact (50 FR 41265, October 9, 1985).
The Safety Evaluation dated November 6, 1985 related to this action and the above referenced submittals by the licensee are available for public inspection at the Comission's Public Document Room 1717 H Street, N.W., Washington, D.C.
- 20555, and at the Waterford Public Library, 49 Rope Ferry Road, Waterford, Connecticut 06385.
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A copy of the Safety Evaluation may be obtained upon written request to the U.S. Nuclear Regulatory Commission, Washington, D.C.
20555, Attention: Director, Division of Licensing.
These exemptions.are effective upon issuance.
Dated at Bethesda, Maryland this 6th day of November.1985.
FOR THE NUCLEAR REGULATORY COMMISSION n
Hu L. Thompso, J., D rector Di sion of Licens Office of Nuclear Reactor Regulation
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